This invention relates to a passenger restraint belt system for use with vehicles, ships, airplanes and other conveyances.
For example, Japanese Utility Model Publication No. 2-7094 discloses a vehicle occupant restraint belt system which includes an emergency lock retractor (ELR) as shown in FIG. 26. The emergency lock retractor has a shaft 102 around which a seat belt 103 is looped. The shaft 102 is drivingly connected to an electric motor 109 operable on command from a control unit to rotate the shaft 102 in a normal direction retracting the seat belt 2 into the retractor and in a reverse direction pulling the seat belt 2 out of the retractor. The emergency lock retractor is associated with an emergency lock mechanism 104.
Referring to FIG. 27, the control unit includes a slack setting circuit 124 connected to a brake switch 116, a vehicle speed sensor I17 and an accelerator switch 116. The brake switch 116 is associated with the brake pedal and it produces a signal indicative of the application of braking to the vehicle. The vehicle speed sensor 117 is provided to sense the speed of running of the vehicle and it produces a brake application signal indicative of the sensed vehicle speed. The accelerator switch 116 is associated with the accelerator pedal and it produces a deceleration signal when the accelerator pedal is released. The slack setting circuit 124 operates in response to the signals from the brake switch 116, the vehicle speed sensor 117 and the accelerator switch 118 to calculate a desired degree of slack to be produced in the seat belt 103. The desired slack degree is fed from the slack setting circuit 124 to a control circuit 127 which thereby controls the first and second relays 128 and 129 to operate the electric motor 109 in the normal or reverse direction so as to adjust the slack in the seat belt 103 to the desired degree calculated by the slack setting circuit 124. The produced belt slack is effective to provide a tensionless condition where a predetermined degree of margin exists around the seat passenger when the seat belt is in passenger restraining position. The control unit controls the retractor to retain the tensionless condition when the vehicle is running at a very slow speed or at rest, and to eliminate the slack in the seat belt 103 in the presence of vehicle braking when the vehicle is running at a slow speed or in the presence of vehicle deceleration when the vehicle is running at a fast speed. The control unit locks the retractor with no slack in the seat belt 103 when a vehicle collision is anticipated based on brake- and accelerator-pedal operations. The control unit can provide a great degree of slack in the seat belt 103 in normal vehicle driving conditions.
Referring to FIG. 28, description will be made to another vehicle occupant restraint belt system disclosed in Japanese Patent Application No. 2-100218. This vehicle occupant restraint belt system includes interior elements CL1 mounted to the vehicle body. Each of the interior elements CL1 is associated with corresponding one of actuators included in the driving means CL2 and it has a state variable with respect to the passenger. The vehicle occupant restraint belt system also includes a detecting means CL3 for collecting vehicle collision data. The collected vehicle collision data are fed to a behavior estimating means CL4 which estimates a passenger's behavior based on the vehicle collision data including an impact to the passenger. The collected vehicle collision data are also fed to a computing means CL5 which receives the estimated passenger's behavior from the behavior estimating means CL4. The computing means CL5 calculates characteristic values of the respective interior elements in a manner to minimize the impact to the passenger in accordance with the estimated behavior. The calculated characteristic values are fed to a control means CL6 which thereby controls the respective actuators CL2 for driving the corresponding interior elements CL1.
Referring to FIGS. 29A and 29B, the detecting means CL3 is taken in the form of a laser radar 169 used to detect the speed of the vehicle relative to the one in front just before a vehicle collision. The behavior estimating means CL4 and the computing means CL5 calculate an optimum seat belt load varying characteristic based on the detected relative speed. The control means CL6 controls the corresponding actuator included in the driving means CL2 to realize the calculated optimum seat belt load varying characteristic. The actuator is taken in the form of a combination of an adjustable load clamp 133 provided in the emergency lock retractor 131 and a preloader 135.
Referring to FIG. 30, there is shown still another vehicle occupant restraint belt system which employs a preloader type emergency lock retractor operable in response to the G waveform transmitted from the vehicle body. With such a conventional vehicle occupant restraint belt system, however, the length or stroke the seat belt is retracted is limited by the length of sliding movement of the piston 141 within the cylinder 139. For this reason, the belt retracting stroke cannot be increased without increasing the size of the retractor.